The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section

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dc.contributor.advisorDyer, Robert Aen_ZA
dc.contributor.authorNgaka, Tshebeletso Christianen_ZA
dc.date.accessioned2017-06-06T09:36:42Z
dc.date.available2017-06-06T09:36:42Z
dc.date.issued2017en_ZA
dc.description.abstractBackground: It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery. In this prospective, observational, non-inferiority study we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height. Methods: Two groups of 25 parturients, Group O (BMI >40 kg/m²) and Group N (BMI <32 kg/m²) requiring elective cesarean delivery were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine co-administered with 10 μg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first thirty minutes following spinal anesthesia, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate. Results: There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes, or by temperature at 5 minutes. At 25 minutes, there was a two-dermatome difference in median block height for loss of temperature sensation between Group O and Group N (T2 vs. T4, 95% confidence interval (CI) of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 μg (0-900 μg), and 100 μg (0-1250 μg) in Group N and O respectively. The 95% CI for the difference between the two median doses was -150 μg to 100 μg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in Group O than in Group N (49.1 vs 39.4 minutes, 95% CI difference 1.7 to 17.7 minutes). The mean time for recovery of touch sensation to T10 was longer in Group O (152 vs 132 minutes, 95% CI difference 3.8 to 36.2 minutes). No analgesic supplementation was required. Conclusion: Only a minor increase block height as assessed by temperature occurred in Group O at 25 minutes. Vasopressor requirements during the first 30 min of SA were equivalent. Time for regression of SA block level was longer in the Group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients.en_ZA
dc.identifier.apacitationNgaka, T. C. (2017). <i>The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Department of Anaesthesia. Retrieved from http://hdl.handle.net/11427/24485en_ZA
dc.identifier.chicagocitationNgaka, Tshebeletso Christian. <i>"The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Department of Anaesthesia, 2017. http://hdl.handle.net/11427/24485en_ZA
dc.identifier.citationNgaka, T. 2017. The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Ngaka, Tshebeletso Christian AB - Background: It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery. In this prospective, observational, non-inferiority study we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height. Methods: Two groups of 25 parturients, Group O (BMI >40 kg/m²) and Group N (BMI <32 kg/m²) requiring elective cesarean delivery were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine co-administered with 10 μg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first thirty minutes following spinal anesthesia, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate. Results: There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes, or by temperature at 5 minutes. At 25 minutes, there was a two-dermatome difference in median block height for loss of temperature sensation between Group O and Group N (T2 vs. T4, 95% confidence interval (CI) of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 μg (0-900 μg), and 100 μg (0-1250 μg) in Group N and O respectively. The 95% CI for the difference between the two median doses was -150 μg to 100 μg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in Group O than in Group N (49.1 vs 39.4 minutes, 95% CI difference 1.7 to 17.7 minutes). The mean time for recovery of touch sensation to T10 was longer in Group O (152 vs 132 minutes, 95% CI difference 3.8 to 36.2 minutes). No analgesic supplementation was required. Conclusion: Only a minor increase block height as assessed by temperature occurred in Group O at 25 minutes. Vasopressor requirements during the first 30 min of SA were equivalent. Time for regression of SA block level was longer in the Group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients. DA - 2017 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2017 T1 - The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section TI - The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section UR - http://hdl.handle.net/11427/24485 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/24485
dc.identifier.vancouvercitationNgaka TC. The influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean section. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Department of Anaesthesia, 2017 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/24485en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Anaesthesiaen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherAnaesthesiologyen_ZA
dc.titleThe influence of body mass index on sensorimotor block and vasopressor requirement during spinal anaesthesia for elective caesarean sectionen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMMeden_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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